如何设置UILabel的内边距？

最近在项目中，有个地方需要设置UILabel的内边距，即字体和Label控件之间的间隙。UILabel不像UIButton那样，有个contentEdgeInsets、titleEdgeInsets、imageEdgeInsets供我们设置文字或图片与按钮边界的界限，所以我们只能另外想其他办法来实现。其实，办法也很简单，只需要我们自定义UILabel，然后重写drawTextInRect:方法即可实现我们的目标。

CustomLabel.h

#import <UIKit/UIKit.h>

@interface CustomLabel : UILabel

@property (nonatomic, assign) UIEdgeInsets textInsets; // 控制字体与控件边界的间隙

@end
           

CustomLabel.m

#import "CustomLabel.h"

@implementation CustomLabel

- (instancetype)init {
    if (self = [super init]) {
        _textInsets = UIEdgeInsetsZero;
    }
    return self;
}

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        _textInsets = UIEdgeInsetsZero;
    }
    return self;
}

- (void)drawTextInRect:(CGRect)rect {
    [super drawTextInRect:UIEdgeInsetsInsetRect(rect, _textInsets)];
}

@end
           

Demo.m

CustomLabel *titleLabel    = [[CustomLabel alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 100.f, 24.0f)];
titleLabel.backgroundColor = [UIColor whiteColor];
titleLabel.textColor       = [UIColor blackColor];
titleLabel.font            = [UIFont systemFontOfSize:12.0f];
titleLabel.textInsets      = UIEdgeInsetsMake(0.f, 15.f, 0.f, 0.f); // 设置左内边距